Short communication
Evaluation of an antigen-based test for hospital point-of-care diagnosis of SARS-CoV-2 infection

https://doi.org/10.1016/j.jcv.2021.104838Get rights and content

Highlights

  • Overall sensitivity, specificity, NPV and PPV of SARS-CoV-2 Ag Test on the LumiraDx™ Platform were 90.3%, 92.1%, 95.1%, and 84.9%, respectively, compared to RT-PCR results.

  • LumiraDx POCT identified 89.3% and 92.1% of SARS-CoV-2 RT-PCR positive patients in symptomatic and asymptomatic group, respectively.

  • False positive antigen testing results in both symptomatic and asymptomatic group were achieved.

Abstract

Background

An accurate diagnosis is essential to identify and manage SARS-CoV-2 infected patients and implement infection control measures. Although real-time reverse transcription polymerase chain reaction (RT-PCR) is the current recommended laboratory method, several rapid antigen point-of-care tests (POCTs) were developed as frontline testing for SARS-CoV-2 infection diagnosis.

Objectives

The aim of this study was to assess a recently CE-approved POCT, SARS-CoV-2 Ag Test on the LumiraDx™ Platform (LumiraDx GmbH, Cologne, Germany) for the identification of SARS-COV-2 infected subjects at hospital setting.

Methods

LumiraDx POCT was implemented in three hospital settings: adult and pediatric emergency departments and occupational medicine department along two-month period during the second peak of Italian SARS-CoV-2 pandemic. Rapid antigen testing was performed on direct nasal swabs and results were compared with those obtained by Xpert Xpress SARS-CoV-2 assay.

Results

Overall sensitivity, specificity, NPV and PPV were 90.3%, 92.1%, 95.1%, and 84.9%, respectively, compared to reference method. Sensitivity, specificity, PPV and NPV for symptomatic group were 89.3% [95% IC 84.2-93.3], 88.2% [95% IC 72.5-96.7], 97.8% [95% IC 94.6-99.1], and 58.8% [95% IC 48.4-68.5], respectively. Sensitivity, specificity, PPV and NPV for asymptomatic group were 92.1% [95% IC 85-96.5], 92.3% [95% IC 89.9-94.4], 67.9% [95% IC 61.3-73.8], and 98.5% [95% IC 97.1-99.2], respectively. False positive and negative antigen testing results in both symptomatic and asymptomatic group were observed.

Conclusion

SARS-CoV-2 Ag POCT may represent an interesting tool to rapidly identify symptomatic or asymptomatic infected subjects. However, in hospital setting in which false negative or false positive results may have relevant implications, confirmatory NAAT always remains necessary for the appropriate management of patients.

Keywords

SARS-CoV-2
Antigen test
Point-of-care-testing
Hospital screening
Healthcare workers

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